For those who aren't familiar with Viewfinder, it is a search front-end for Flickr. Viewfinder will let you filter for certain licenses (such as Creative Commons), and gives you easy access to the proper links to use for attribution. Viewfinder does not connect to your Flickr account. It doesn't upload pictures, and it won't let you view your friends' timelines. It's meant to help you find pictures on Flickr. We've mentioned Viewfinder for iPhone before, but this is an app which definitely benefits from iPad's larger screen.
You could just use Flickr.com on the iPad for this, but Viewfinder makes it faster, better looking, and easier. If you spend a lot of time on Flickr, it's definitely worth the $9.99 asking price. Viewfinder will save a history of your downloads, making it easier to go back and find or verify license types and links to the images.